In an op-ed published in Dagens Nyheter, the former spokespersons write there is a growing conflict between the party's leadership and members calling for a more environmentally focused platform.
They say the party has given up too much to its ruling partners the Social Democrats. They also say leadership is not taking the criticism to heart.
As a result, they write, the Greens are dropping in the polls and losing members. The party earned 6.9 percent of the vote in Sweden's 2014 general election. A poll published Thursday by Ipsos found it pulling in just 4 percent of the vote.
"In short, the party is under stress, on the verge of an acute crisis situation," the former leaders wrote.
2016 has been a tumultuous year for the party. It first entered government back in 2014 but this year saw a string of gaffes and high-level resignations that rocked the party.
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